Figure 8. Time Line Constraints for Three Representative Spacecraft, Depicted in the S3 Scheduling HTML5 GUI.

(a) Example of multiple time line requirements applied to a single spacecraft, here GRAIL A, one of a pair of lunar orbiters. There is a gap
constraint and a minimum tracking time constraint in a 24-hour UTC day (both violated and colored red); there is also a requirement to
track on all three DSN complexes within a 48-hour period (satisfied). (b) Example of a gap constraint between ranging passes only, that is,
ignoring the intervening tracking passes. In this example, the second maximum gap requirement has been violated and the resulting interval is colored red. (c) Example of a recorder time line constraint applied to the STEREO A/B mission pair, showing the violation of the constraint in an interval where the accumulated data would exceed the recorder capacity. Note that the recorder volume drops more quickly
when a 70-meter contact (such as DSS- 63) is scheduled, due to the higher downlink data rate. The STEREO spacecraft also have a requirement to schedule at least one track per week at each complex, here satisfied only for STEREO B.